/*
 * This code provides a glue layer between PhysicsFS and Simple Directmedia
 *  Layer's (SDL) RWops i/o abstraction.
 *
 * License: this code is public domain. I make no warranty that it is useful,
 *  correct, harmless, or environmentally safe.
 *
 * This particular file may be used however you like, including copying it
 *  verbatim into a closed-source project, exploiting it commercially, and
 *  removing any trace of my name from the source (although I hope you won't
 *  do that). I welcome enhancements and corrections to this file, but I do
 *  not require you to send me patches if you make changes.
 *
 * Unless otherwise stated, the rest of PhysicsFS falls under the GNU Lesser
 *  General Public License: http://www.gnu.org/licenses/lgpl.txt
 *
 * SDL falls under the LGPL, too. You can get SDL at http://www.libsdl.org/
 *
 *  This file was written by Ryan C. Gordon. (icculus@clutteredmind.org).
 */

#include <stdio.h>  /* used for SEEK_SET, SEEK_CUR, SEEK_END ... */
#include "physfsrwops.h"

static int physfsrwops_seek(SDL_RWops *rw, int offset, int whence) {
	PHYSFS_file *handle = (PHYSFS_file *) rw->hidden.unknown.data1;
	int pos = 0;

	if (whence == SEEK_SET) {
		pos = offset;
	} /* if */

	else if (whence == SEEK_CUR) {
		PHYSFS_sint64 current = PHYSFS_tell(handle);
		if (current == -1) {
			SDL_SetError("Can't find position in file: %s",
			             PHYSFS_getLastError());
			return(-1);
		} /* if */

		pos = (int) current;
		if ( ((PHYSFS_sint64) pos) != current ) {
			SDL_SetError("Can't fit current file position in an int!");
			return(-1);
		} /* if */

		if (offset == 0)  /* this is a "tell" call. We're done. */
			return(pos);

		pos += offset;
	} /* else if */

	else if (whence == SEEK_END) {
		PHYSFS_sint64 len = PHYSFS_fileLength(handle);
		if (len == -1) {
			SDL_SetError("Can't find end of file: %s", PHYSFS_getLastError());
			return(-1);
		} /* if */

		pos = (int) len;
		if ( ((PHYSFS_sint64) pos) != len ) {
			SDL_SetError("Can't fit end-of-file position in an int!");
			return(-1);
		} /* if */

		pos += offset;
	} /* else if */

	else {
		SDL_SetError("Invalid 'whence' parameter.");
		return(-1);
	} /* else */

	if ( pos < 0 ) {
		SDL_SetError("Attempt to seek past start of file.");
		return(-1);
	} /* if */

	if (!PHYSFS_seek(handle, (PHYSFS_uint64) pos)) {
		SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
		return(-1);
	} /* if */

	return(pos);
} /* physfsrwops_seek */


static int physfsrwops_read(SDL_RWops *rw, void *ptr, int size, int maxnum) {
	PHYSFS_file *handle = (PHYSFS_file *) rw->hidden.unknown.data1;
	PHYSFS_sint64 rc = PHYSFS_read(handle, ptr, size, maxnum);
	if (rc != maxnum) {
		if (!PHYSFS_eof(handle)) /* not EOF? Must be an error. */
			SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
	} /* if */

	return((int) rc);
} /* physfsrwops_read */


static int physfsrwops_write(SDL_RWops *rw, const void *ptr, int size, int num) {
	PHYSFS_file *handle = (PHYSFS_file *) rw->hidden.unknown.data1;
	PHYSFS_sint64 rc = PHYSFS_write(handle, ptr, size, num);
	if (rc != num)
		SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());

	return((int) rc);
} /* physfsrwops_write */


static int physfsrwops_close(SDL_RWops *rw) {
	PHYSFS_file *handle = (PHYSFS_file *) rw->hidden.unknown.data1;
	if (!PHYSFS_close(handle)) {
		SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
		return(-1);
	} /* if */

	SDL_FreeRW(rw);
	return(0);
} /* physfsrwops_close */


static SDL_RWops *create_rwops(PHYSFS_file *handle) {
	SDL_RWops *retval = NULL;

	if (handle == NULL)
		SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
	else {
		retval = SDL_AllocRW();
		if (retval != NULL) {
			retval->seek  = physfsrwops_seek;
			retval->read  = physfsrwops_read;
			retval->write = physfsrwops_write;
			retval->close = physfsrwops_close;
			retval->hidden.unknown.data1 = handle;
		} /* if */
	} /* else */

	return(retval);
} /* create_rwops */


SDL_RWops *PHYSFSRWOPS_makeRWops(PHYSFS_file *handle) {
	SDL_RWops *retval = NULL;
	if (handle == NULL)
		SDL_SetError("NULL pointer passed to PHYSFSRWOPS_makeRWops().");
	else
		retval = create_rwops(handle);

	return(retval);
} /* PHYSFSRWOPS_makeRWops */


SDL_RWops *PHYSFSRWOPS_openRead(const char *fname) {
	return(create_rwops(PHYSFS_openRead(fname)));
} /* PHYSFSRWOPS_openRead */


SDL_RWops *PHYSFSRWOPS_openWrite(const char *fname) {
	return(create_rwops(PHYSFS_openWrite(fname)));
} /* PHYSFSRWOPS_openWrite */


SDL_RWops *PHYSFSRWOPS_openAppend(const char *fname) {
	return(create_rwops(PHYSFS_openAppend(fname)));
} /* PHYSFSRWOPS_openAppend */


/* end of physfsrwops.c ... */

